I. Field of the Invention
The present invention relates generally to fluid filtering devices and, more particularly, to such a device adapted for connection with the return line of the hydraulic fluid system.
II. Description of the Prior Art
There are a number of previously known fluid filtering devices and many of these devices are particularly adapted for connection with a hydraulic fluid system. Such systems typically include a fluid reservoir fluidly connected by a suction line to a hydraulic pump. The outlet from the hydraulic pump is in turn connected to the hydraulic system which ultimately returns the hydraulic fluid to the reservoir via a return line. It is the conventional practice to connect a fluid filter to either the suction or return line of the hydraulic system in order to remove unwanted debris from the hydraulic fluid. Otherwise, this debris enters and can damage the hydraulic system.
These previously known hydraulic fluid filtering devices typically comprise a housing having an inlet port and an outlet port with a fluid filtering chamber defined within the interior of the housing. A filter element is then removably positioned through a housing opening into the filter chamber so that, upon doing so, the filter element is fluidly positioned in between the inlet and outlet ports. A closure cap then covers the housing opening and retains the filter element in position. In addition, many of these previously known fluid filtering devices include a bypass valve means for directly fluidly connecting the inlet port with the outlet port at a predetermined differential pressure across the filter element indicative of excessive filter element clogging.
These previously known fluid filtering devices, however, suffer from a number of different disadvantages. One disadvantage of these previously known devices is that workmen, either intentionally or through inadvertence, neglect to insert the filter element within the filter chamber and instead simply connect the closure cap across the housing opening. By doing this, however, the fluid inlet port is directly connected with the outlet port so that debris entrained within the hydraulic fluid passes directly to the hydraulic system. As previously described, such debris can damage the components of the hydraulic system.
A still further disadvantage of these previously known fluid filtering devices with bypass valve assemblies is that the differential pressure across the filter element at which the bypass valve assembly opens is preset upon the manufacture of the fluid filtering device and cannot be adjusted or reset once the device is installed in a hydraulic fluid system. Moreover, many of these previously known bypass valve assemblies are mounted directly to the device housing so that the entire device must be removed from the fluid system and disassembled when repair or replacement of the bypass valve assembly is required. Such removal of the entire fluid filtering device is not only expensive and time consuming to accomplish but also results in excessive downtime for the entire hydraulic system.
A still further disadvantage of these previously known fluid filtering devices is that such devices have not proven entirely satisfactory in removing metallic particles from the hydraulic fluid and this is particularly true when the fluid filtering device is in a fluid bypass condition. Hydraulic fluid systems are particularly susceptible to damage from metal particles, chips and filings in the hydraulic fluid.